1. Field of the Invention
The present invention relates to a vinyl chloride resin composition suitable for powder molding and a method for preparing the same.
2. Description of the Prior Art
As covering materials of interior parts of automobiles, resinous molded articles with high quality appearance are used which have light weights and good soft feeling, and also leather grain, stitch and the like on their decorative surfaces.
Such molded articles are produced by powder molding a vinyl chloride resin composition for powder molding comprising a granular vinyl chloride resin in which, plasticizers, stabilizers, pigments and the like are dry blended and also a fine powder vinyl chloride resin is uniformly dispersed.
A typical example of the interior parts of the automobiles which uses such molded articles as the covering materials is an instrument panel.
In these years, automobiles installing an air bag for an assistant seat in an instrument panel have been widely used. As such air bags, air bags are proposed which are installed under the covering materials of instrument panels for hiding and break the covering materials to inflate in operation.
It is required for molded articles used as such covering materials of instrument panels under which such an air bag is installed to break the covering materials by inflation, and also to prevent the scattering of broken pieces on breaking at low temperature and form the broken pieces having less sharp edges, that is, to have a sufficient elongation at low temperature. An example of such covering materials is a molded article produced by powder molding a vinyl chloride resin composition for powder molding which has been prepared using a relatively large amount of a plasticizer during dry blending.
Instrument panels are often heated to high temperature. Thus, molded articles used as the covering materials of such instrument panels are required not to contain materials which evaporate at high temperature and adhere to and cloud windshields. That is, the molded articles should have low glass-hazing properties.
In general, vinyl chloride resin compositions for powder molding are required to be easily molded and to provide molded articles having less irregular thicknesses. Thus, such resin compositions should have good powder-cutting off and melting properties.
However, there have been no vinyl chloride resin compositions for powder molding which have a sufficient elongation at low temperature, provide molded articles having low glass-hazing properties, and have excellent powder-dropping and melting properties.